This invention relates to a computer system constructed and having certain components arranged to provide relatively high airflow through the enclosure thereof in a manner that lessens associated acoustic noises, and having its electrical elements requiring cooling arranged to best take advantage of the airflow. The invention also relates to a method of constructing such a system and in arranging the referenced components and elements.
A long standing problem in computer systems has been the difficulty in providing in an effective, economical and reliable manner sufficient cooling of electrical elements that require temperature management, such as high power system boards, multiple CPU modules and power sources. The providing of the necessary high airflow cooling for such elements creates an concomitant problem of high levels of acoustic noises. This is particularly undesirable with respect to certain high end deskside and under-the-desk workstation computer systems when located, for example, in a one person office setting. In the first instance the concern is to avoid damage to the elements in question caused by over heating, in the latter the concern is to improve the working environment of the persons using the systems.
It has been the general practice in such systems to arrange the hardware heat generating elements in a common enclosure, for example heat sensitive elements such as system boards, power supply units, CPU modules, graphics, S bus and PCI cards, disk drives etc. Such systems do not allow all of the elements in need of cooling to be strategically located to obtain the most effective cooling in terms of the paths of the airflow of the fans and/or blowers provided for cooling the elements. A particular problem in this regard is presented in systems having a large number of disk drives, CPU, graphics and PCI modules and/or cards and multiple power supply units, which represent great heat generating sources. In addition the airflow paths are not utilized to the best advantage to maximize the supplied cooling, but instead are interfered with by components, parts and the structures of the systems, which interferences in turn require higher fan speeds than what otherwise would be required to force the air through the systems and do not allow the flow of air to be evenly distributed throughout the systems. Also, in past systems as to the need to use higher fan speeds, the lack of ample intake and exhaust areas in the enclosures increased airflow impedance which also increased the acoustic noises. In these systems in many cases the high speed fans or blowers are usually arranged at the back of the enclosures adjacent to the power supply unit or units, while other electrical elements also requiring cooling may be located a distance from the fans or blowers.
The referenced problems and conditions, together with the manner of supporting certain of the elements and components of the systems, such as the power supply units, disk drives, fans and blowers and enclosure side walls, and the inherit high airflow impedance condition not only fostered a situation that created acoustic noises but allowed the amplification thereof. The high impedance condition is created by the system construction that requires air to move or be pushed through small cooling holes, tight spaces and around bends, all of which reduce airflow and require an increase in the pressure of the cooling air. The selection of fan speed in the past to provide the required cooling has been influenced by the size, type and number of fans that the limited space available in the enclosure would allow, which space when exhausted left the only option to increase the speed of the fans in an attempt to overcome the conditions noted above. The speed and type of the fans is a major source of acoustic noise of the systems, both as to the direct noise i.e. fan rotational noise and the indirect noise i.e. vibrational noises and air resistance of various elements caused by the high speed fans and high airflow impedance of the systems.
Also a problem in certain computer system designs is to allow the presence of preheated air in the vicinity of certain of the critical electrical elements requiring cooling. This preheated air is created by the critical elements and other adjacent hardware elements. This condition necessitates an increase in fan airflow to increase the convection cooling rate to compensate for the preheated ambient air temperature in the vicinity of the sensitive elements, which requirement then increases the acoustic noise of the system.
It is a common characteristic of present day computer systems to offer to the trade a basic system, which is adapted to several different use configurations. While the configurations may have different internal electrical elements, they all have a group of similar electrical elements and a common enclosure which makes up the basic system. In this marketing concept the acoustic noise is constant for all configurations of the basic system, for example whether the configuration is intended for a server room, a workstation area or a one person office setting. This manufacturing and marketing scheme represent a disadvantage in not being able to provide a computer system in terms of noise level that is the quietest system for a particular operating setting. For example, it necessitates placing the same basic system from a noise level standpoint in a server room, where a high noise level can be tolerated, and in an office setting where a high noise level can be objectionable.